John McEnroe at Wimbledon, July 2011. Photo: Julian Finney/Getty Images

Each week, Lizzy Goodman guides you through the dirty streets of rock and roll.

It’s almost impossible to upstage a real rock star. Part of the fun of going to splashy bold name attended rock events – like the one I went to this week, a listening of the new MetallicaLou Reed collaboration album Lulu, held at the Steven Kasher gallery in Chelsea – is watching very famous celebrities act like giddy touristy school kids around rockers like Lars Ulrich and Lou Reed. So imagine my surprise when, about an hour into the event, someone showed up who turned everyone’s head: John McEnroe.

Full disclosure: I am a tennis dork. Like, I follow all those ATP dudes on Twitter and am actually genuinely compelled by tweets about training regimens and fantasy football teams and charity events they are supporting. So it’s not surprising that I would wig out upon seeing the tennis legend in person. But it is surprising that Lou Reed would. (Reed didn’t swoon or anything but he smiled a lot, which for him counts as effusive).

I showing up at this gallery and headed straight for the bar, running smack into Richard Belzer, Law and Order star, comic, and laconic conspiracy theorist. (Second only to tennis is my love for Law and Order. This was so my night). Beltzer is just as tall as you think and was wearing velour bedroom slippers – the kind you imagine get left for you in the really good suites at the Ritz in Paris – and walking with a cane. He wears sunglasses at night, obviously. I downed two glasses of free, surprisingly decent red wine and made the rounds.

I’m not going to talk about the art because I’m fond of the if-you-can’t-say-anything-nice rule, however, in the back room, there were displaying some pretty rad Anton Corbijn shots of Metallica and Reed posed gritty urban rocker style in a series of desolate gravely outdoor spaces like train tracks and abandoned whatevers. It’s awesome when distinguished rocker dudes embrace that kind of arms crossed get off my lawn pose but with wrap-around shades on and while wearing expensive denim.

Anyway, the rhythm of the room went like this: there was a secret back space behind the bar where all the bold names were stashed and periodically one or two of them would emerge and mill around. Cocktail waitress girls would shout descriptions of the hors d’oeuvre (stuffed figs or little pieces of rare steak served on plates so overloaded with floral garnish they looked like funeral arrangements) into their ears because the record was being played so loudly no one could hear anything else.

The hoi polloi, elite enough to have gotten into this party to begin with, were therefore not inclined to stare at the main attractions just because, hey, that’s Lou Fucking Reed wearing bizarre space age basketball shoes and sampling a stuffed fig. But of course there were some superfans in the house (the dude in the Metallica Yankee jersey gets special points) and Lars or Lou or Kirk would take a few pics with them then go shuffling back into the secret special room.

When McEnroe showed up in his blazer and skull t-shirt the seas parted. He marched right up to Reed, around whom there had formed a little radius of attention, and they embraced. He then proceeded to act much more like a normal human than any other famous person there, which of course is the coolest thing a celeb can do. He hit the bar in the front, had a beer, took about 700 photos with a bunch of people who five minutes ago were acting like they were doing due diligence at an office cocktail party but were now suddenly flushed with fandom. Had another beer. Looked bored and agitated by all the attention. Then split.

“That’s it,” I asked him as he exited just behind me. “For now,” he said, warily. (Who was I and what did I want?!) I asked him how many photos he’d snapped in the ten minutes he was inside. “More than I’d like.” He didn’t even snag the free Bowers and Wilkins headphones they were gifting on the way out the door. (Though not to me, I got a pamphlet that tells me all about the prize I am not famous enough to receive). As I hopped in a cab on my way East, McEnroe was on the street, brow furrowed and texting. Johnny Mac had other places to be.